First off I want to say I had a great time talking with Rob and Joker at EM 2009 and I really appreciate them putting together some interesting projects. I'm going to put both kits (I have the Benjolin working and I still have to put together the Zeitgeist) and a power supply in one box but I have some questions I'm hoping someone can answer:

Zeitgeist:
1. There are two jumpers. One is for the power connection but what is the other one for?
2. There are two headers. I'm assuming that one allows switching between CV control and LDR control of the delay time but what does the other header control?
3. What does each knob control? I'm assuming one knob controls the delay time and one knob controls feedback, but what about the other two?
4. Is there an opamp issue and if so how can it be resolved?

These two devices were offered at a couple DIY workshops that Rob and Joker were giving at the EM-2009 (and elsewhere). They are Rob's designs so I would not feel comfortable posting the schematics (not trying to be difficult but I'm sure he put a lot of time into them). Did you get to build them?

The Power Supply I'm using for my Benjolin is a surplus switching supply I picked up. It has +24VDC, +5VDC, +12VDC, and -12VDC outputs at various load capacities. The + - 12 VDC outputs are rated at 350 ma, and seem to be quite ample.

Thanks for the info! On the paperwork the term "header" refers to the two 3 prong headers (one of which is to turn the Light sensor on and off). It's confusing because I've always used the term header for power connectors etc. Thanks for the tip on the opamp I knew Rob was having issues with it. I got my power supply in an old medical equipment enclosure that was provided at the Baltimore workshop (with Peter Blasser). Ken stone offers a board for a power supply (you'll have to order the parts from Mouser etc.). You can go to his web site "www.cgs.synth.net" and look for the "+/- 15 Volt Power Supply" which you can adapt to +/- 12 v (by changing the regulators).

Hi, I am new to this forum and to DIY in general. I attended the Benjolin workshop in Baltimore but the kits didn't arrive in time for us to build them while Rob and Joker were there. I was able to build almost all of the Zeitgeist today but in order to finish it I have a few (probably stupid) questions:

1. I have all major components soldered on to the board. However, my kit does not have anything that appears to be a 3-pin header. Are these necessary (or more specifically what are they for)?

2. How do I connect 1/4 inch jacks to the input and output. The kit didn't come with jacks but I bought a few neutrik 1/4" slim jacks..it looks like I need to solder two wires to the jack and then I'll need some kind of connecter to attach to the header pins on the board? Is closest to the jack the ground? Also, if I connect the output jack ground to the ground header pin what does the input jack ground connect to?

3. The kit came with 2 metal toggle switches, where do these go? I don't see any mention on them on the instructions or diagram.

4. Once I get it working I'd like to connect it to the CV outs of the Benjolin. Any ideas how I would do that? is that what the other 5 pins on the 5x2 header are for?

Again, sorry if these are very basic questions but I'm a bit lost and would really like to get this kit up and running.

Hi, I am new to this forum and to DIY in general. I attended the Benjolin workshop in Baltimore but the kits didn't arrive in time for us to build them while Rob and Joker were there. I was able to build almost all of the Zeitgeist today but in order to finish it I have a few (probably stupid) questions:

1. I have all major components soldered on to the board. However, my kit does not have anything that appears to be a 3-pin header. Are these necessary (or more specifically what are they for)?

These connect to the two switches. The idea is to solder the two pieces of coloured threewire cable through the three holes marked 'header' on the PCB on one side of the cable and the switches on the other side of the cable.

One switch will switch the audio output to the point right before the delayline or right after the delayline.
The other switch will switch between the LDR (or any other resistive) sensor or the delaytime modulation CV input on the 2x5 header.

bartlebooth wrote:

2. How do I connect 1/4 inch jacks to the input and output. The kit didn't come with jacks but I bought a few neutrik 1/4" slim jacks..it looks like I need to solder two wires to the jack and then I'll need some kind of connecter to attach to the header pins on the board? Is closest to the jack the ground? Also, if I connect the output jack ground to the ground header pin what does the input jack ground connect to?

The middle two pins in the 2x5 row of pins are the ground to all other connections. So basically you just connect the gnd from both jack connectors to this gnd on the PCB.

bartlebooth wrote:

3. The kit came with 2 metal toggle switches, where do these go? I don't see any mention on them on the instructions or diagram.

See answer to question 1

bartlebooth wrote:

4. Once I get it working I'd like to connect it to the CV outs of the Benjolin. Any ideas how I would do that? is that what the other 5 pins on the 5x2 header are for?

Connect it to the gnd pins on the 2x5 header and one of the pins right next to the gnd. Pot two will set the modulation depth.

bartlebooth wrote:

Again, sorry if these are very basic questions but I'm a bit lost and would really like to get this kit up and running.

The Benjolin can run on a dual supply of +/-12V to +/18V, as it has its own +9V and -9V regulators on board. Optionally, 9V batteries can be connected after the regulators, which the regulators don't mind as long as there is ónly batteries or ónly a power supply connected! (Don't connect both batteries and a power supply at the same time to prevent possible explosion of the batteries!)
The Benjolin uses roughly 60mA of current.

The Zeitgeist has a +5V regulator that accepts a power supply voltage of +6V to +20V. It can easily share the +12V to +15V that also powers the Benjolin. The Zeitgeist uses roughly between 20mA and 40mA of current, depending on the delaytime.

electri-fire wrote:

oscilloclast wrote:

the "+/- 15 Volt Power Supply" you can adapt to +/- 12 v (by changing the regulators).

I don't know if this is really necessary. Voltageregulators need 3 Volt surplus input, but work with higher voltage as well. May get a little warmer I suppose, and there's no heatsinks.

So here's a question: Could we use +/- 15Volts or will things get too hot?

(note: I didn't build the Zeitgeist yet , but I think it needs a single supply doesn't it?)

I got everything working and I am currently mounting everything in a case (the Peter B case which fits the boards perfectly). I noticed a few things about the kits and I just wanted to check and make sure that everything was working properly.

Benjolin:

1. Osc 2 pulse out is weaker/thinner sounding then Osc Pulse out. Is this the way it was designed?

2. The filtered out is a lower volume then the other outs. If this is the way it was designed is there any way to increase the filtered output to the level of the others? I’m going to be running these kits with my modular so the more signal I can get out the better. If there is nothing on the PCB I can do I’ll just increase the signal with an opamp.

Zeitgeist:

The output switch selects between “delayed signal” and “delayed signal + input signal”. Is that correct?

For the LDR it looks like there are two places on the board where it can be connected: one on the “sensor” input on the 10 pin header and one on the two prong header by the switch to select CV or LDR (for control of the delay time). Is that correct?

Thanks for putting together these kits, I’m having a great time exploring them! (the range of different sounds is incredible).

I got everything working and I am currently mounting everything in a case (the Peter B case which fits the boards perfectly). I noticed a few things about the kits and I just wanted to check and make sure that everything was working properly.

Benjolin:

1. Osc 2 pulse out is weaker/thinner sounding then Osc Pulse out. Is this the way it was designed?

When the rungler crossmodulation pots are closed both pulses should be about 50%, so basically a square wave. There might be a slight difference in timbre, but it shouldn't be very different. Check if the levels are the same, then it should be fine.
But when rungler modulation on especially oscillator B is used the pulsewidth starts to vary wildly and should give a constantly changing timbre in the rhytm of oscillator A.

oscilloclast wrote:

2. The filtered out is a lower volume then the other outs. If this is the way it was designed is there any way to increase the filtered output to the level of the others? I’m going to be running these kits with my modular so the more signal I can get out the better. If there is nothing on the PCB I can do I’ll just increase the signal with an opamp.

Totally correct, the filter output is at line level so you can plug it into a line level input amplifier. All other outputs swing roughly between +5V and -5V and can so be used as input signal for a modular system.

The filter output is directly connected to the last pole output of the filter, so there is nothing to do there. Increasing the filter input level would overload the filter and also drastically explode the all harmonic distortion in the filter. So, a preamp to amplify it to analog synth input level would be the way to go. An amplification of roughly 20dB should do the trick.

oscilloclast wrote:

Zeitgeist:

The output switch selects between “delayed signal” and “delayed signal + input signal”. Is that correct?

Yes, it switches the output 'pre-delayline' or 'post-delayline'.

oscilloclast wrote:

For the LDR it looks like there are two places on the board where it can be connected: one on the “sensor” input on the 10 pin header and one on the two prong header by the switch to select CV or LDR (for control of the delay time). Is that correct?

It should best be connected to the two prong header.

oscilloclast wrote:

Thanks for putting together these kits, I’m having a great time exploring them! (the range of different sounds is incredible).

A suggestion for the Benjolin kit. A drilling template for the pots and mount holes on the PCB would add to the coolness of the kit. I'm sure your PCB artwork has the domensions for the centers of the pots...Would make panel drilling easier. Something with the centers marked ( with a plus symbol) that a person could put on a panel and then center punch to locate drilling holes?

A suggestion for the Benjolin kit. A drilling template for the pots and mount holes on the PCB would add to the coolness of the kit. /../ Something with the centers marked ( with a plus symbol) that a person could put on a panel and then center punch to locate drilling holes?

I would welcome that. Especially because I like the feel of the pots as is.
I wouldn't want to have to mask missdrillings with a larger knob on top.

Mike Hunter here. I was the guy with the really long hair at the workshop at EM2009.

Here's a picture of my Benjlin and ZeitGeist built, together, into a wooden box...and not quite finished yet.

I've added a small amp and speaker behind the reproduction antique grille cloth. I'm going for that retro early 20th century look...

The blue patch cord allows the user to patch the Benjolin to the ZeitGeist (or to patch other effects inbetween.) the empy jack is to patch the output of the ZeitGeist to an external amp. If left unplugged, the audio goes to the build in amp and speaker.

You cannot post new topics in this forumYou cannot reply to topics in this forumYou cannot edit your posts in this forumYou cannot delete your posts in this forumYou cannot vote in polls in this forumYou cannot attach files in this forumYou can download files in this forum

Please support our site. If you click through and buy from our affiliate partners, we earn a small commission.